The present invention relates to a storage system, a data migration managing system, and a data migration managing method. More particularly, this invention relates to a technique to safely migrate data between logical devices and to prevent alteration such as rewriting or deletion.
Because of the growing demand for security functions in storage systems and to comply with laws and regulations regarding the handling of electronic data, there is an increasing need for a technique to prevent alteration, such as rewriting or deletion, of data written in storage systems and to store the data for a certain period of time. For example, Japanese Patent Laid-Open (Kokai) Publication No. 2005-18568 suggests a technique to prevent alteration, such as rewriting or deletion, of data written in logical devices by setting a read-only attribute for each logical device of storage systems and suppressing any change of the read-only attribute for a certain period of time.
On the other hand, data life cycle management (DLCM) has gained the attention of the public as another technical trend besides the prevention of alteration. DLCM is the concept of realizing cost-efficient data management by migrating data between storage systems based on the value of the data changing over time. For example, a mailing system is the backbone system for a company and, therefore, requires high-end storage systems that exhibit high performance and high reliability. Since access to mail dated several weeks ago becomes less frequent, the relevant data is migrated from high-end storage systems to near-line storage systems. The near-line storage systems are inferior to the high-end storage systems in their performance and reliability, but they have the advantage of low cost and are still accessible at any time. When one or two years have passed since the migration of the data to the near-line storage systems, the data is further migrated to a tape medium, which is then stored in a depository. According to the concept of DLCM, data migration management is important in order to reduce the cost of data management.
As an example of a data migration management technique, Japanese Patent Laid-Open (Kokai) Publication No. 2003-58397 discloses a file managing apparatus for, when storing a file in an information storage device connected to a network, managing a file storage deadline in the information storage device that stores the file and automatically migrating the file to another storage device before the file storage deadline. Moreover, Japanese Patent Laid-Open (Kokai) Publication No. 2004-78331 discloses a file relocation system for migrating a file that has been stored in a common storage area beyond a specified storage deadline, to a safe area, migrating the file that has been stored in the safe area beyond a specified storage deadline, to an external storage device, and restoring the file to the source storage area when a computer or a file server makes reference to the file.